Striking letter automatic wheel printer for use on flat surfaces



Nov. 8, 1966 R E. HISS 3,283,869

STRIKING LETTER AUTOMATIC WHEEL PRINTER FOR USE ON FLAT SURFACES Filed Oct. 26, 1964 5 Sheets-Sheet 1 Arron 5y Nov. 8, 1966 R. E. HISS 3,283,869

STRIKING LETTER AUTOMATIC WHEEL PRINTER FOR'USE ON FLAT SURFACES Filed Oct. 26, 1964 5 Sheets-Sheet 2 l mm '1 AMA 7oz. /d/Mia 5/4/55,

1966 R. E. HISS 3,283,869

STRIKING LETTER AUTOMATIC WHEEL PRINTER FOR USE ON FLAT SURFACES Filed Oct. 26, 1964 5 Sheets-Sheet 5 Mum/a1. 5y flax/4x0 5 My,

R. E. HISS OMATIC WHEEL PRINTER FLAT SURFACES Nov. 8, 1966 STRIKING LETTER AUT FOR USE ON 5 Sheets-Sheet 4 Filed Oct. 26, 1964 Wrawmz 5. 445:,

Nov. 8, 1966 R. E. HISS 3,283,869

STRIKING LETTER AUTOMATIC WHEEL PRINTER FOR USE ON FLAT SURFACES Filed Oct. 26, 1964 5 Sheets-Sheet 5 Ava/Wan $614450 5 A0, 55 ZvAA L MW United States Patent Ofi ice Patented Nov. 8, 1966 3,283,869 STRIKING LETTER AUTOMATIC WHEEL PRINTE FOR USE ON FLAT SURFACES Richard E. Hiss, Orcus Island, Wash., assignor to Hughes Aircraft Company, Culver City, Calif., a corporation of Delaware Filed Oct. 26, 1964, Ser. No. 406,373 Claims. (Cl. 197-2) This invention relates generally to a high-quality printer which can be used with an X-Y plotter, and more particularly relates to a mechanical printer that can be operably positioned along an X-axis and a Y-axis for selectively printing characters upon a surface.

In automatic drafting with an X-Y plotter, it is desirable to apply printed characters to a print surface with speed and accuracy. Thus programmed pen movement is not satisfactory because of an inherent lack of pen speed and inherent inertial forces resulting from such complex pen movement.

One approach is to apply the characters by means of a mechanical printer. Heretofore, a problem with this appoach has been that mechanical printers which have a large character capacity, also have a large weight and size. As a result, the inherent inertial forces created during movement of the printer decreased the quality of the print-ing or else necessitated a slowing down of the printer speed to compensate for overshoot, oscillations, and the like.

Accordingly, it is an object of this invention to provide a high-quality, lightweight printer having a large character capacity.

Another object is to provide an improved printer for use in conjunction with an X-Y plotting board.

Still another object is to provide a printer in which the print characters can be accurately spaced and printed along one of several transverse print lines.

Yet another object is to provide an improved printer which prints high quality characters upon a surface at a high speed without bouncing, double hitting, skipping, or smearing the characters.

A further object is to provide a printer which is able to print in small corners and which develops low inertial forces during movement.

A still further object is to provide an improved printer in which :the type characters can be easily cleaned and/ or replaced.

The above and other objectives of this invention can be accomplished by providing an XY plotting board having a pair of intersecting arms which are programmed to move independently of one another along an X-axis and a Y- axis, respectively. A carriage having a pen means and a printer is mounted to rollably ride along the two intersecting arms, in accordance with the program, thereing configuration about its periphery. To select specific pieces of type, a shaft positioning motor is actuated in a controllable manner to rotate a required or selected type on the print wheel under a hammer means. Once the selected type is positioned in registry with the hammer, an indexing pin further accurately positions and holds the print wheel, whereupon the hammer reciprocally drives a character formed on the end of the selected type into contact with an inked ribbon and the printing surface. To insure a clear printing of the character, a predetermined increment of inertial free fall is all-owed in the type at the end of the hammer stroke, thereby preventing double hit, bounce, skipping, or smearing of the character.

After the character is printed and the type is raised above the print surface, the carriage is moved laterally to the next adjacent space and another selected type moved into position under the hammer. Thereafter, the above printing sequence can be continued.

If it becomes necessary to print along a line which is transverse to the above described print line, the printer can be rotatably positioned within the carriage to eifectively reorient the position of the hammer. Once the printer is so rotated degrees for example) a selected type can be positioned under the hammer and the previously described printing sequence initiated. Of course, it should be understood that other angles of rotation could be used such as degrees. When the printer is rotated it would then become necessary to program the intersecting arms of the plotting board to compensate for character reorientation and for parallax change of the hammer relative to the two movable arms.

Other objects, features, and advantages of this invention will become apparent upon reading the following detailed description of one embodiment of the invention and referring to the accompanying drawings in which:

FIG. 1 is atop plan view of an X-Y plotter illustrating the operative relationship of a carriage having the printer of this invention positioned thereon;

FIG. 2 is an enlarged top plan view of the printer without the carriage;

FIG. 3 is :a sectional view of the printer taken along the line 3-3 of FIG. 2 in which a print head indexing means and a clutch means connected to a common drive shaft are illustrated in cross section;

FIG. 4 is a side elevation view of the printer as seen from the right-hand side of FIG. 2 or FIG. 3;

FIG. 4a is an enlarged cross-sectional view of a V- shaped indexing slot taken along line 4a-4a of FIG. 4;

FIG. 5 is an enlarged cross sectional view of a camo-perated reciprocable hammer means of the printer; and

FIG. 6 is an enlarged perspective view of a hinged support ring for the printer.

Referring to the drawings, FIG. 1 illustrates an automatic drafting machine of the type including an X-Y plotter 12 having a pair of intersecting arms 13 and 14 movably mounted to extend across the surface thereof. The intersecting arms 13 and '14 are moved in position at specific coordinates on the X-axis and the Y-axis, re spectively, by an appropriate control means such as illustrated in US. Patent No. 3,143,804, issued August 11, 1964, to W. J. Muldoon, entitled Interrupted Line Drawing System.

A carriage 16 is slidably mounted on the two intersecting .arms 13 and 14 and is carried into position at specific intersecting coordinates by movement of the two intersecting arms 13 and 14. As is conventional, a set of inking pens 18 can be secured to the carriage 16 and lowered into contact with the surface of a drawing material such as paper 17. A .pen mechanism of the type which could be used is illustrated in US. Patent No. 3,127,678, issued April 7, 1964, to W. I. Muldoon, entitled Pen Positioning Circuit.

A printer assembly 21 embodying the principles of this invention is mounted upon the carriage .16 in a plane parallel to and above the surface of the drawing paper 17. Thus, as the carriage 16 is moved to specific intersecting coordinates above the paper, the printer 21 is also carried into position. Compensation for the parallax difference between the position of the inking pens 18 and the position of the character on the printer 21 is provided by circuitry of the type described in the above referenced US. Patent No. 3,143,804. 1 v

Referring now to the details of the printer 21, as illustrated in FIGS. 2-4 a print wheel 22 is rotatably stepped so that a selected one of a plurality of pieces of type 23, which are mounted above the peripheral region of the print wheel, is positioned under a cam-actuated hammer 24 so that a character formed on the end of the selected type 23 can be reciprocally driven into contact with the paper 17. To perform this print operation, a clutch 26 is actuated by solenoid 27 so that a rocker arm shaft 28 is rotated. During this rotation of the rocker arm shaft 28, an indexing pin 29 is lowered into contact with one of a plurality of V-shaped indexing or detent slots 30 formed at equally spaced intervals in a track on the upper surface of the print wheel 22. When the print wheel 22 is so indexed, a cam-actuated hammer 24 is reciprocally driven into contact with the selected type, whereupon the character formed on the lower end of the type is inertially driven into contact with a printing surface such as the paper 17.

Referring'now to the details of the printer 21 illustrated in FIGS. 2-4, a mounting plate 31, having a plurality of mounting apertures 32 formed about its peripheral region, provides a support structure for the printing mechanism. The mounting apertures 32 are adapted to receive bolts or other mechanical fasteners for conmeeting the mounting plate 31 to the carriage 16 in a manner to be explained.

To angularly position the print wheel 22 a shaft position means is mounted on the upper surface of the mounting plate 31 and includes a four-position stepping motor 33 having a 16-toone step down gear head. A motor drive shaft 34 projects vertically downwardly from the gear head through an aperture in the mounting plate 31.

A mounting hub 36 is secured to the motor drive shaft 34 by means of set screws 37 or other appropriate mechanical fasteners. A collar 38 is formed about the circumference of the hub 36.

An encoder disk 39 is fitted onto the hub 36 against the collar 38 and is locked against rotation by the key 41. This encoder disk 39 can be of the Gray coded type having six bits and therefore 64 discrete angular positions. The angular position of the encoder is detected by a mechanical brush contact means 42 which includes a separate brush for each bit. 'I'hus, electrical contact is made with specific ones of the brushes so that a binary coded signal is conducted to a stepping motor control circuit (not shown). Shaft position control circuits of this type are conventional and operably compare the digital signal from the encoder disk 39 to a desired digital signal so as to actuate the stepping motor 33 until such times as coincidence occurs between the pickedoif signal and the desired signal. One type of circuit which could be used to perform this operation is illustrated and described in US. Patent No. 2,909,769, issued October 20, 1959, to C. P. Spaulding, entitled Code Comparison and Control System.

The lightweight print wheel 22 is also fitted onto the central hub 36 and locked against angular rotation by the key 41. Thereafter, a capping screw 43 is threaded into the end of the hub 36 to maintain the print wheel 22 and the encoder disk 39 in stacked position and to prevent axial movement thereof.

The peripheral region of print-ing wheel 22 has a channel 44 formed thereabout. The thin radially projecting walls 45 and 46 of the channel 44 have a plurality of equally spaced superposed aperture pairs formed therethrough. In practice, there is one aperture pair for each discrete position on the encoder disk 39 and for each V-shaped detent slot 30. An advantage of having thin wall portions on the print wheel is that the mass is kept low, thereby reducing the inertial forces developed during movement.

A plurality of pieces of type 23, each having a separate character formed on the lower end thereof, are

slidably mounted for reciprocal axial motion in individual ones of the apertures. By positioning the type 23 about the periphery of the print wheel 22, an advantage of high character capacity-to-weight and to size is attained, thereby reducing inertia and allowing printing to be done near the corners of the X-Y plotter. A coil spring 48 encircles the body of each type 23 and is secured to the body portion and held under compression [against the lower wall 45 of the channel. As a result, the type 23 is normally maintained in its retracted position as illustrated in FIG. 4. Thus, when the top end of the type 23 is struck by the hammer 24, as will be explained shortly, the type character is driven reciprocally downward into contact with the surface of the paper 17 whereupon a character is printed.

To protect the above described encoder and print wheel mechanism, a cylindrical housing 49 is mounted to project vertically downward from the lower surface of the mounting plate 31 thereby enclosing the structure.

Referring now to the details of the drive mechanism mounted on the top of mounting plate 31, a constantly running motor 51 is secured to a motor mounting bracket 52 which is in turn secured to the top of the mounting plate 31. A toothed drive pulley 53 is secured to a motor output shaft 54 and drives a cogged flexible belt 56. The cogged flexible belt 56 in turn rotates a toothed driven pulley 57 which can have enough mass to act as a. flywheel for an intermittently driven printing mechanism.

The intermittently driven printing mechanism is fastened to the top of the mounting plate 31 by a support bracket 61 having a base portion 62 which is in turn secured to the upper surface of the mounting plate 31 such that two spaced-apart support arms 63 and 64 project vertically upward from the base 62. A clutched drive shaft 66 is rotatably mounted to extend through the two support arms 63 and 64 on an axis of'rotation just below the axis of rotation of the rocker arm shaft 28. The rocker arm shaft 28 is also rotatably mounted to extend between the two spaced-apart support arms 63 and 64.

To rotate or rock the rocker shaft 28, a cam 67 is mounted on the clutched drive shaft 66 so that a cam follower 68 which is secured to the rocker shaft 28 provides a rocking motion for the bell crank rocker arm 69 against the bias torque force applied to the rocker shaft by a torsion coil spring 71 secured to the end of the rocker shaft. When the rocker arm 69 rotates, it drives the hammer 24 in a reciprocating manner. The indexing pin mechanism 29 is also actuated by the rotation of the clutched drive shaft 66 and engages a detent slot 30 in the printer wheel 22 (as previously explained) by operation of an eccentric crank and linkage mechanism 72 which is in turn secured to the end of the drive shaft 66.

Referring now to the details of the intermittently driven printing mechanism (FIG. 3), the continuously driven pulley 57 is mounted for independent rotation about the drive shaft 66 whereupon torque can be transferred to the drive shaft 66 when a normally disengag d one revolution helical spring clutch 73 is engaged. The driven pulley 57 is rotatably mounted on the drive shaft 66 by means of a bearing 74 so that a hollow clutch drum 76 is rotated independently of the drive shaft 66. A clutch coil spring 77 is mounted to encircle the drum 76. A tang 78 at one end of the coil spring 77 extends radially outward into one of a plurality of slots 79 formed at one end of an independently rotatable clutch collar 81. A tang 82 formed on the other end of the clutch coil spring 77 extends radially inward into a slot in torque transfer cap 83 which is in turn secured to rotate with the drive shaft 66.

In clutch operation, the solenoid 27 has a retractable stop 86 which is normally held against a projection 87 on the clutch collar 81 by a retaining spring 88. With the stop 86 in this position, the clutch coil spring 77 is spirally opened to provide clearance between the inside diameter of the clutch spring 77 and the clutch drum 76.

When the solenoid 27 is actuated, the stop 86 is retracted against the spring force, thereby allowing the clutch collar 81 to rotate as the spring spirally closes to a smaller inside diameter. As the clutch coil spring 77 closes, its inside diameter frictionally engages the clutch drum 76 whereupon the torque forces from the drum further tighten the clutch spring upon the drum. As a result, the torque from the driven pulley 57 is transferred to the drive shaft 66 through the clutch coil spring 77 to the tang 82 which extends into the torque transfer cap 83.

After the projection 87 has had a chance to rotate beyond the top of the retractable finger 86, the solenoid 27 can be de-energized, whereupon the coil spring 88 returns the stop 86 to its initial position against the periphery of the clutch collar 81. As a result, after the clutch has made a complete revolution, the projection 87 on the outer surface of the clutch housing is again engaged by the retractable stop 86, whereupon the clutch coil spring 77 is again spirally opened thereby removing the torque from the drive shaft 66. To stop backward rotation of drive shaft 66 when the clutch coil spring 77 is opened, a ratchet cam 89 is engaged by a flexible blade or pawl 90 at the end of a complete revolution of the drive shaft 66. f

To insure that the print characters are properly positioned, the indexing means 29 is actuated to engage one of the integrally spaced indexing slots 30 formed in a track on the upper surface of the print wheel. In operation, an off-center crank pin 91 connected to one end of the drive shaft 66 converts the rotary motion of the drive shaft to linear reciprocal motion through a link 92. The lower end of link 92 is pivotally connected to reciprocally drive a hollow plunger 93 which is in turn slidably mounted for reciprocal motion within a guide housing 94. The lower end of guide housing 94 is formed with an outward extending foot or base portion through which mechanical fastening means extend to secure the guide housing to the upper surface of the mounting plate 31.

A retractable indexing pin 96 is mounted within a bore portion 95 of the hollow plunger 93 and is biased in an axially extending position by a compressible coil spring 97. As the plunger is lowered, the indexing pin 97 is lowered through an aperture 98 formed through the mounting plate 31. The tapered point of the indexing pin 97 is positioned to engage the V-shaped side walls of a detent slot or indexing slot 30 which is in substantial registry with it, whereupon the print wheel 22 can be angularly displaced into exact registry with the axis of the indexing pin if it has not already been properly positioned. An advantage of this indexing is that any variation in the angular accuracy of the stepping motor 33 is corrected for by the indexing pin 96, thus insuring accuracy and reliable operation. As the hollow plunger 93 is driven lower, the indexing pin 96 retracts against the biasing force of coil spring 97, therebypreventing substantial axial forces from being applied to the print wheel 22 while, at the same time, preventing angular rotation thereof for an extended or major portion of a complete revolution of the drive shaft 66. Once the print wheel 22 is so indexed, the cam-operated hammer 24 can be actuated by further rotation of the drive shaft 66.

Referring now to FIGS. 2, 3 and 5, in actuating the hammer 24, the circular arc cam 67 is rotated one revolution with the drive shaft 66. As the cam rotates, the cam follower roller 68 is arcuately moved first away from and then back toward the axis of the drive shaft 66, During travel of the cam follower roller 68 the rocker arm 69 is arcuately pivoted on the rocker airm shaft 28 to impart an oscillatory motion to a tappet 101 of the bell crank rockerarm 69.

As the tappet 101 oscillates, it drives a hammer mass 102 vertically downward against the counteracting force of a lifter coil spring 103. As the hammer mass 102 is driven reciprocally downward, a hammer head 104 is driven against the upper end of the type 23 which is in registry or axial alignment with it. The type 23 is in turn driven reciprocally downward (as previously explained) to move an inked ribbon 106 downward sandwiched between the raised character on the lower end of the type and the print surface 17.

Now referring to the hammer 24 in more detail, a hollow cylindrical guide housing 107 is for-med integrally with the base 62 of the support bracket 61. The upper end of the guide housing 107 is open and has a sleeve 108 of low friction material fitted or secured about the inner housing wall. The hammer mass 102 is slidably mounted within the sleeve 108 for axial movement within the sleeve bore 109. To stop the hammer mass 102 at a lower limit of travel, a reduced diameter flange 111 is formed toward the lower end of the guide sleeve 108. The lower end of the hammer mass 102 is formed with an axially projecting boss 112 to which is secured the longer cylindrical shaft having a hammer head 102. The hammer head extends vertically downward from the boss through a coaxially aligned aperture 113 formed through the base 62. The lifter coil spring 103 is mounted within a recess 114 formed on the lower end wall of housing 107 and extends axially upward through the bore 109 to the lower end of hammer mass 102. To secure the hammer 24 to the upper surface of mounting plate 31, an aperture 116 is formed through the support bracket base 62 whereupon a conventional fastener, such as a set screw 117, can be fitted therethrough.

Downward motion and energy is applied along the axis of the hammer 24 from the tappet 101 by means of the upper s-t'em member 118. The stem member 118 is externally threaded and secured to the hammer mass 102 at the tapped blind aperture 119. A jam nut 121 is threaded downward and against the upper surface of the hammer mass 102 in a conventional manner to prevent rotation of the stem member 118. The tip 122, of the stem member 118 is made of some strong durable metal and is arranged to contact the tappet 101.

In order to provide consistent high quality print characters, a predetermined amount of inertial free-fall is operably constructed into a hammer. On the down stroke the lowermost portion of the tappet 101 travels downward a maximum distance X, as illustrated by the dotted line fragmentary portion of FIG. 5. During this down stroke, inertial forces are imparted to the hammer mass 102, whereupon once the tappet 101 reaches its lowermost position the hammer mass 102 continues to travel downward an added increment of free fall AX against the force of lifter coil spring 103. During the major portion of the downward travel X and the incremental portion AX, the type 23 is driven downward to print a character on the print surface 17, as previously explained. An important advantage of this free-fall arrangement is that a relatively consistent impact force is applied to the print surface at each printing while at the same time skipping or double-bouncing of the type is prevented. Once the type 23 strikes the print surface, the inertial energy of the hammer mass 102 is dissipated and the return stroke of the hammer begins.

During the return stroke, the tappet 101 is moving back upward under the influence of the torsion spring 71 which is secured to a slot, the outer end thereof (FIGS. 2 and 3) and to a retainer bracket on the leg 64. At the same time the coil spring 103 returns the hammer mass 102 vertically upward, the tip 122 again contacts the tappet 101, whereupon the hammer 24 is returned to its initial raised position.

On the backstroke the rocker arm 69 also trans-ports or incrementally moves the inked ribbon 106 by means of a linkage member 123. The lower end of the linkage member 123 is pivotally secured to the rocker arm 69 while the upper end is operably secured to a conventional ribbon cartridge 124 of the type illustrated in FIG. 1. This ribbon cartridge and carrier is of a conventional type such as the trademarked IBM Selectric cartridge described in US. Patent No. 2,986,260 and further described in the instruction booklet entitled IBM Selectric copyrighted 1962 by International Business Machines Corporation.

After the end of the return stroke, the printer 21 can be moved along the X or Y-axis and the print wheel 22 rotated to move another type 23 having a different character under the hammer 24. Thereafter, the above-described indexing and printing sequence can be again continued.

As illustrated schematically in FIG. 1, the printer 21 is arranged to print across the X-axis of the XY plotter. If instead it is desired to print up or down the Y-axis, the printer 21 can be rotated within a hinged support ring 126 (FIG. .6). One edge of the support ring 126 is hingeably connected to one rollable follower bar 127 of the carriage 16 by a double-leaf hinge 128. A second follower bar 129, which is rollably mounted on the other intersecting arm 13, includes a stop member 131 formed at the outermost end thereof. The hinged support ring 126 has a substantially tangentially projecting hasp 132 formed thereon so that when the support ring 126 is hingeably lowered, the hasp 132 rests on the stop member 131. An aperture 133 formed through the hasp is constructed and arranged to be in substantial registry with a threaded aperture in the stop member 131 when the hasp rests on top of it. A fastener such as a bolt can be then screwed into the two apertures to secure the support ring 126 in a plane parallel to and spaced above the print surface 17. An .important advantage of this hinge arrangement is that the printer 17 can be swung upward to expose the type 23 of the print wheel for cleaning or replacement when the two povrtions are unbolted.

To reorient the type characters for printing along a different axis, a plurality of spaced-apart receiving apertures 136 are formed about the body portion of the support ring 126. Corresponding apertures 32 are formed through the mounting plate 31 of the printer as previously explained. When the apertures 32 and 136 are brought into substantial registry with one another, fasteners such as threaded bolts, machine screws or other devices can be threadably fastened into the lower threaded apertures 136 to clamp the printer 21 in the new position. Of course, it should be understood that other orienting printer means such as a locking pawl in which either the support ring 126 or the support base 31 of the printer is formed with a plurality of serrations or apertures while the nonapertured member would have a spring-loaded pawl or catch secured to it and arranged to engage the serrations. Another approach would be to use quick disconnect clamps and so forth.

Although one embodiment has been herein illustrated and described, it will be appreciated by those skilled in the art that numerous variations may be made in the details and in the organizational aspects of the assembly herein described without departing from the spirit and the scope of this invention. Accordingly, it is intended that the foregoing description and the showings made in the drawings shall be considered only as illustrative of the principle of this invention and are not to be construed in a limiting sense.

What is claimed is:

1. In a device for use to print on a surface of an X-Y axes coordinate plotter,

movable support bars carried by the plotter in deter mined relation to the X-Y coordinates,

a carriage supported by the bars for movement therewith,

said device being supported by the carriage and comprising a mounting plate,

a shaft located in a central area of the plate and projecting downwardly therethrough,

a print wheel carried by the shaft adjacent the lower terminal thereof and immediately above the surface, a plurality of movable type units carried annularly around the wheel and movable toward and away from the surface,

said wheel being rotatable about the axis of said shaft,

a plurality of locating elements adjacent each type unit,

each element being in determined relation to a specific unit,

power means carried by the plate and operatively connected to the print wheel to provide primary controllable and rotatable indexing of the latter,

movable index control means carried by the plate and operative to selectively engage the respective locating elements to secondarily accurately position the related type unit in a print position,

movable hammer means carried by the plate to impact engage the type unit in print position to induce rapid movement of the latter to print engage the surface,

means to induce sequential movement of the index control means and the hammer means to first position the index control means and then induce movement of the hammer means to impact engage the related type unit,

said last-mentioned means comprising a power source and a continuously driven flywheel,

' a first normally stationary shaft,

clutch means to selectively interconnect the flywheel and the first shaft to induce rotation of said first shaft,

a second normally stationary shaft,

means operatively interconnecting the second shaft and the index control means,

and a driving connection between said first shaft and said second shaft to induce reciprocating rotatable movement of the second shaft in response to rotational movement of the first shaft.

2. A printing device according to claim 1,

wherein said index control means comprises a pin carried on the base plate for movement toward and away from said wheel,

and a link interconnecting the first shaft and the pin whereby rotation of the first shaft induces said pin movement,

said locating elements comprising notches in the print wheel to receive the end of the pin.

3. A printing device according to claim 2,

wherein said driving connection between said first and second shafts comprises a rocker arm on said second shaft having a cam follower at one end thereof and an extension tappet at the other end thereof,

said tappet engaging said hammer means,

and a cam on said first shaft engageable with the cam follower whereby rotation of the first shaft induces reciprocating movement of the second shaft and rocker arm providing reciprocating movement of the hammer means.

4. A printing device according to claim 3,

wherein said mounting plate is carried by the carriage for selectable rotatable movement relative thereto whereby the plate may be positioned relative to the carriage and printing undertaken in desired relation to the X-Y axes.

5. A printing device according to claim 4,

wherein said plate is pivoted to the carriage and may be arcuately moved relative thereto to provide access to the print wheel for service.

References Cited by the Examiner UNITED STATES PATENTS 479,085 7/1892 Beauregard 1972 535,607 3/1895 Whitaker 197-2 1,271,231 7/1918 Schroder 197604 (Qther references on following page) 9 10 UNITED STATES PATENTS 3,032,166 5/1962 Watson 197-66 X 918 It 3,059,750 10/1962 Schnellmann 197-66 $11,15 197 2 3,135,195 6/1964 Potter 1111-93 5 195 Hueber 197, 6 6 3,142,247 7/1964 Sweeney 101-93 11 195 Beccio 197 53 X 5 1 8/1 Dr jza 101-93 1 1959 spaulding 34 347 3,145,650 3/1964 W ight 10193 3 19 1 FI-eedson 197 .148.451 9/1964 Morris et a1. 33-18 8/1961 Shepard 101-93 9/1961 Gun 61 et a1. 197 6 6 ROBERT E. PULFREY, Przmary Exammer. 3/1962 Wasserman 101-93 10 E. S. BURR, Assistant Examiner. 

1. IN A DEVICE FOR USE TO PRINT ON A SURFACE OF AN X-Y AXES COORDINATE PLOTTER, MOVABLE SUPPORT BARS CARRIED BY THE PLOTTER IN DETERMINED RELATION TO THE X-Y COORDINATES, A CARRIAGE SUPPORTED BY THE BARS FOR MOVEMENT THEREWITH, SAID DEVICE BEING SUPPORTED BY THE CARRIAGE AND COMPRISING A MOUNTING PLATE, A SHAFT LOCATED IN A CENTRAL AREA OF THE PLATE AND PROJECTING DOWNWARDLY THERETHROUGH, A PRINT WHEEL CARRIED BY THE SHAFT ADJACENT THE LOWER TERMINAL THEREOF AND IMMEDIATELY ABOVE THE SURFACE, A PLURALITY OF MOVABLE TYPE UNITS CARRIED ANNULARLY AROUND THE WHEEL AND MOVABLE TOWARD AND AWAY FROM THE SURFACE, SAID WHEEL BEING ROTATABLE ABOUT THE AXIS OF SAID SHAFT, A PLURALITY OF LOCATING ELEMENTS ADJACENT EACH TYPE UNIT, EACH ELEMENT BEING IN DETERMINED RELATION TO A SPECIFIC UNIT, POWER MEANS CARRIED BY THE PLATE AND OPERATIVELY CONNECTED TO THE PRINT WHEEL TO PROVIDE PRIMARY CONTROLLABLE AND ROTATABLE INDEXING OF THE LATTER, MOVABLE INDEX CONTROL MEANS CARRIED BY THE PLATE AND OPERATIVE TO SELECTIVELY ENGAGE THE RESPECTIVE LOCATING ELEMENTS TO SECONDARILY ACDURATELY POSITION THE RELATED TYPE UNIT IN A PRINT POSITION, MOVABLE HAMMER MEANS CARRIED BY THE PLATE TO IMPACT ENGAGE THE TYPE UNIT IN PRINT POSITION TO INDUCE RAPID MOVEMENT OF THE LATTER TO PRINT ENGAGE THE SURFACE, MEANS TO INDUCE SEQUENTIAL MOVEMENT OF THE INDEX CONTROL MEANS AND THE HAMMER MEANS TO FIRST POSITION THE INDEX CONTROL MEANS AND THEN INDUCE MOVEMENT OF THE HAMMER MEANS TO IMPACT ENGAGE THE RELATED TYPE UNIT, SAID LAST-MENTIONED MEANS COMPRISING A POWER SOURCE AND A CONTINUOUSLY DRIVEN FLYWHEEL, A FIRST NORMALLY STATIONARY SHAFT, CLUTCH MEANS TO SELECTIVELY INTERCONNECT THE FLYWHEEL AND THE FIRST TO INDUCE ROTATION OF SAID FIRST SHAFT, A SECOND NORMALLY STATIONARY SHAFT, MEANS OPERATIVELY INTERCONNECTING THE SECOND SHAFT AND THE INDEX CONTROL MEANS, AND A DRIVING CONNECTION BETWEN SAID FIRST SHAFT AND SAID SECOND SHAFT TO INDUCE RECIPROCATING ROTATABLE MOVEMENT OF THE SECOND SHAFT IN RESPONSE TO ROTATIONAL MOVEMENT OF THE FIRST SHAFT. 